The Beast Inside
by That-Aussie-Writer
Summary: Derek has shadows in his eyes, and Stiles doesn't know what to do. Danger is around every corner and soon Stiles will find out that there's more to Derek than anyone thought. When Derek and Stiles end up on the run from a horde of undead, tensions are high, but will other kinds of tensions come to light when they are forced to spend every waking moment together? ZOMBIES. STEREK. AU


**Chapter | ONE:** Shadows

Derek Hale had shadows in his eyes. His normal grey gaze was overrun with gloom and Stiles wasn't sure what to do. He stood awkwardly by his bedroom window, having just let Derek in, and stared at the man's shoes, studying them for lack of anything else to do. When Derek shifted on the bed, just slightly, nothing more than a twitch of his knee, Stiles jumped and raised his eyes, finding the shadowed gaze locked on his face.

Licking his lips in preparation of speaking, Stiles opened his mouth, hoping some words would spill from his throat. Hoping for anything to come out, it didn't matter what, just as long as it was words. Hell, they didn't even need to be coherent. When nothing but a stuck little noise sounded Stiles closed his mouth and clenched his teeth shut then dropped his eyes. He heard, rather than saw, Derek move on his bed. Another shift of his knee.

"It's not like you to be speechless."

Stiles let his eyes jump up, finding Derek still watching him with a curious expression on his face. The shadows were still there, gathering and growing larger with each passing second. Did Derek know he had shadows in his eyes? That he looked like some lost puppy which had been kicked outside by its owner? Stiles didn't think so.

He let his mouth drop open again and this time words came out, in a rush, a messy, disjointed and disorganised rush. "I'm not speechless, I just don't know what to say," yep, because that isn't being _not_ speechless at all. "I'm wondering what the hell you're doing here at well past midnight, why you couldn't have waited until morning and knocked on the front door like any normal person," he disregarded that fact that he would frequently climb into Scott's bedroom window to see him instead of using the front door. "And I'm wondering why you showed up with dark eyes and a lost puppy expression on your face."

Derek's dark eyebrows were slowly climbing his forehead with every word Stiles said, finally they stopped close to his hairline and he gave Stiles a glare. "Dark eyes? Lost puppy expression?" he parroted back to the teenager. "What are you talking about?"

Stiles shifted, shuffling his feet, before beginning to pace an invisible line on the floor. "Your eyes look like they have shadows in them, not like real shadows, but shadows. You know?" Derek gave him a blank look from the bed. "You don't know. It looks like something is bothering you, something serious. And you look like some puppy who's been scolded by its owner, just real meek and un-Derek-ish." Stiles knew nothing of what he said make a lick of sense to Derek. He was still watching him with shadowed eyes but now there was an emotion flashing through them, it looked like something akin to amusement. But surely Derek Hale didn't do amusement.

Derek ignored everything Stiles said, and instead said, "I need a place to stay." At Stiles' look of surprise he added quickly, "Just for the night."

Stiles, still pacing the imaginary line on the floor, ran his hand through his short hair and blew out a breath of air from his mouth. "What if I say no? What then?"

With a serious expression on his face, Derek replied, "I'll die."

Stiles spluttered on a deep inhale. It wasn't like Derek to be overdramatic, or a drama queen, so Stiles sped up in his pacing, his bare feet padding across the floor. "You're in trouble?" it was half asked, half stated.

Derek nodded, but didn't confirm with words. Instead he stood up abruptly and reached out his hand, grabbing a firm hold of Stiles' wrist. Stiles yelped when the tough fingers squeezed his bone in a tight grip and stopped moving so he wouldn't accidently break his arm by ripping it in Derek's vice-like grip.

"Stop pacing, it's giving me a headache." Derek growled.

"Stopping," Stiles said around a small noise of pain. Derek either didn't know he was hurting him, or didn't care. Probably the latter. "You going to tell me what's going on?" Stiles asked once Derek had let go of his wrist. Stiles checked for bruises immediately, making a show of it, but Derek just clenched his jaw and ignored his dramatics.

"If I tell you, you'll be in danger." Derek said. He moved back to the bed, sitting down on the messy blanket and folding his arms across his chest. Stiles huffed unamused laughter.

"Ok, sure. Yeah." He said. Before stomping to the window and pointing out at the dreary night beyond the glass. "What's out there that has made you run to me with your tail between your legs?"

Derek's eyes narrowed with a fiery glare and Stiles throat worked around a swallow. He dropped his pointing finger after a few moments of absolute silence on Derek's part and then tried again, determined to get to the bottom of things.

"Is it hunters?" he asked, tentatively.

"No."

Derek's face was unreadable. Like a blank document.

"Another wolf?" Stiles tried.

"No."

Derek breathed out an exasperated breath from his nose and then stood suddenly, making Stiles take a step backwards.

"You're not going to tell me are you?" Stiles concluded.

"No." Derek said and Stiles made a noise of annoyance in his throat. Derek didn't seem fazed by the teen's frustration.

"But you expect me to let you stay the night?" Stiles wanted to know.

"Yes."

"Stop answering with one syllable words!" Stile said as loud as he dared.

"Fine."

Stiles looked up in time to catch the sly expression decorating Derek's face and he realised, belatedly, that the man was making a sort of Derek-ish joke. He shook his head and then began pacing, again.

"Will whatever you're hiding from find you? Find us?" Stiles questioned. His voice broke on the last word and betrayed his apprehension despite him trying his best to be nonchalant. Derek moved towards him and snatched his wrist again, holding it in a warm, tight grip. Stiles squeaked, feeling extremely embarrassed by it straight after, and stumbled to a stop. "What's with all the manhandling?"

"I told you to stop pacing." Derek said, his voice a deep rumble. His fingers flexed and he let go, but his glare kept Stiles still. "I doubt what I'm hiding from will find us." He answered Stiles' first question, but ignored the latter one.

"You doubt? You _doubt?_ So, in other words, it could find us? Right?" Stiles was just casually about to have a panic attack.

"I'm hiding out in some random teenager's room. I highly doubt we'll be found."

"Oh so now it's _highly_ doubt? Yeah, because that makes me feel ten times better." Stiles quipped, sarcasm lacing his tone. Derek flashed him his patented I'll-kick-you-ass type glare and Stiles shut his mouth quickly. Before saying, "If you stay the night I have some rules."

Derek crossed his arms over his chest once more but nodded to show he was listening.

"I'm sleeping in the bed, you get the floor,"

"And here I thought we could share." Derek said but it was said in an extremely sardonic manner. Stiles felt the tips of his ears blush at what Derek had implied but schooled his features into a mask of calmness.

"Secondly, you leave in the morning. I don't want my dad to find I've had Derek Hale sleeping in my room. And lastly, if you snore, you're –"

Stiles didn't get to finish his threat, for Derek spoke up, cutting his words short.

"I'll be gone at dawn. And I won't be sleeping." He said.

Stiles blinked at him. "What are you going to be doing then?"

Derek ignored Stiles' words like he hadn't been asking a question. Instead of answering he walked over to the window and stared out at the dark night and tiny, pinprick stars that littered the sky.

"Go to sleep." He said. Or rather, ordered.

Stiles threw up his hands and then stomped over to his bed, he wasn't going to bed just because Derek Hale had said to, he was actually tired and he needed to be up early for school. It had nothing to do with the commanding voice, whatsoever.

He crawled under the covers, pulling them up to his chin and then staring at the back of Derek's head. Derek shifted, like he knew Stiles was staring at him and then turned away from the window to look directly at Stiles. The shadows were there still, in his eyes, hauntingly strong.

"There shadows are still there." Stiles felt the need to say.

Derek blinked at him. "Go to sleep, Stiles." He said, but this time it was softer. Not exactly pleasant, and still an order, but softer nonetheless.

Stiles rolled onto his hip and stifled a yawn with his palm. "Just tell me one thing," he said. Derek's shoulders stiffened. "How bad is the danger of whatever it is you're running from?"

"Dangerous enough."

Stiles huffed out a breath of exasperation. "On a scale of one-to-ten, how bad?"

Derek walked over to him, looming over him like some stretching shadow. Stiles felt the need to sit up, but quelled it. "Ten." Derek said, his eyes shining with so many shadows it looked like he was carrying the weight of worlds on his shoulders. He didn't say anything else, he just moved away from the bed, walking to the window to keep watch. Stiles resisted a shiver.

Realising he wouldn't be able to sleep with Derek awake and wandering around his room Stiles pushed the covers off him and sat up. Derek stared at him.

"I guess I'll keep you company." Stiles said in explanation.

Derek didn't respond. Instead he leaned his shoulder against the wall and stared harder at Stiles. It was unnerving. Unsettling. And Stiles shifted under the scrutiny. Finally Derek spoke.

"So long as you don't push me for answers." He said, agreeing to allow Stiles to stay awake. Not that he could have dictated otherwise. Not really.

* * *

><p>It was at a quarter to two that Stiles heard it; a loud bang that sounded like a gun going off and a door being kicked in all at once. He flinched, half asleep and drowsy from no sleep. Derek was immediately at his bedroom door. Stiles was slow on the uptake, where else Derek knew exactly what had happened.<p>

"What was that?" Stiles asked and he was dismayed to find his voice was an octave higher and sounded startled. Derek didn't turn around from standing near the door. "Derek?"

"Shh," Derek hissed. "Be quiet."

Stiles' eyebrows furrowed and he threw his head like some bad-tempered horse. "Do you think –" he made to say but was cut off by a firm, muscled forearm across his throat. Derek backed him up against the wall and held him still and silent for a few deep breaths and then said, very quietly;

"They've found me."

Stiles' eyes widened in realisation and just as the noise made sense another noise sounded, this one of muffled groans and thumping on the stairs.

"Move!" Derek said and pulled away from Stiles. Removing his forearm and instead striding to the window, he prised it open and looked back at a stunned and silent, for once, Stiles. "Out the window." Derek said, it came across desperate and Stiles felt a panic crashed through his body.

"What's happening? What are we running from? Is my dad safe –?"

Just as his words left his throat he heard his dad shout. There was a thump that sounded, sickly, like metal against flesh and then silence aside from the footsteps coming up the stairs.

Stiles wasn't late on the uptake this time and instead of dashing forward to the window he ran towards his bedroom door.

He didn't get far before strong arms wrapped hastily around his waist, dragging him back against a firm, warm chest that heaved with shallow, rapid breaths.

"You go out there, you leave this room and you're dead." Derek said. There was a deep, snarling note to his voice that made Stiles want to bare his throat, despite being human and not wolf.

"My dad…," Stiles tried to say but Derek hauled him bodily towards the window. "Derek, what about my dad?!" Stiles all but yelled.

Derek didn't say anything. He just pushed Stiles towards the open window. From outside the room Stiles could hear doors banging open and stumbling footfalls.

Stiles' whole body was shaking. His hands trembled and his knees felt like they would buckle. He turned around to find Derek's eyes bright blue and his incisors were on clear display. "What's going on?" Stiles found himself saying.

"I'll tell you later, and we'll come back for your dad, just go. Quickly."

"I can't jump that far without hurting myself." Stiles said, wishing he could get past Derek's bulk and find his dad.

Derek growled low in his throat, his eyes narrowed. "I'll go first and catch you." He promised.

Before Stiles could say anything more Derek was brushing past him and climbing from the window. He jumped effortlessly down to the ground below and then called for Stiles to do the same.

With shaking hands and shivering knees Stiles climbed up onto the window ledge, looking down into the darkness at Derek's bright blue eyes. He perched on the ledge for a pause, listening to the noise outside his door. Then, with a deep breath in, he jumped.

As promised Derek caught him, it was clumsy and messy, and somehow Stiles ended up laying on top of the man, chest to chest and hip to hip. Derek made a snarling noise and pushed Stiles off him quickly.

"Get up. Keep moving." Derek said, roughly.

"Where are we going?" Stiles wanted to know. His heart hammered against his ribs and his teeth chattered from adrenaline and fear.

"Anywhere but here." Derek grunted and then he was taking off at a run. Stiles hesitated for a moment before sprinting after him.

A/N: Please Review. It means a lot to me!


End file.
